event log

> 0   (sequence (capture (some "smile") :x) (backref :x))
> 1   (capture (some "smile") :x)
> 2   (some "smile")
> 3   "smile"
  3 > "smile"
> 4   "smile"
  4 > "smile"
  2 > (some "smile")
  1 > (capture (some "smile") :x)
> 5   (backref :x)
  5 > (backref :x)
  0 > (sequence (capture (some "smile") :x) (backref :x))